The present invention relates to a heating unit being used as a heat source and to a heating apparatus that uses the heating unit, such as electric heaters, cookers, driers and electronic apparatuses (including copying machines, facsimile machines and printers), and more particularly, to a heating unit that uses a carbonaceous substance as a heating element and has excellent heating characteristics as a heat source and to a heating apparatus that uses the heating unit.
Conventional heating units are configured such that a metallic electric heating wire formed of a tungsten wire or the like and formed into a coil shape or a heating element formed into a bar shape or a plate shape is provided inside a glass tube (for example, refer to Japanese Patent Application Laid-Open No. 2001-155692 (see pages 4 to 6, FIG. 7)).
The conventional heating units configured as described above are used as the heat sources of heating apparatuses, such as electric heaters, cookers, driers, copying machines, facsimile machines and printers, and in recent years they are used for various applications as small and efficient heating apparatuses (for example, refer to Japanese Patent Application Laid-Open No. 2003-400267).
Hence, in the case that such a heating unit is incorporated as the heat source of a heating apparatus, such as a cooker, oil and salt scattered from an object to be heated adhere to the heating unit, and contaminants and the like present in the usage environment also adhere thereto, thereby shortening the service life of the heating unit. For this reason, a heat source being long in service life in such harsh usage environment, small in size and high in efficiency, and high in versatility so as to be easily adaptable to various applications has been required. In the field of using such a heat source, providing a heating unit that satisfies the above-mentioned requirements and a heating apparatus that uses such a heating unit has been an important problem.